1. Field of the Invention
The present invention relates to a printing apparatus and a color image printing method, more particularly to a printing apparatus which has a function to perform a high speed color printing and a color image printing method.
2. Descriptions of the Related Arts
There have been heretofore color printers having a function to perform a color printing in a plurality of colors. In conventional color printers, one microprocessor performs conversions to data structures for use in the printers with respect to all colors including cyan, magenta, yellow and black, and controls preparations of image data.
As prior arts concerning the above-described color printers, a technology disclosed in Japanese Patent Laid-Open No. 8(1996)-19542 was proposed. The technology disclosed in this gazette intends a high speed typing, and discloses an image output apparatus which comprises transporting means for transporting paper; a plurality of image output section arranged along the transporting path for the paper transported by the transporting means, each of which outputs an image to the paper simultaneously with others; a plurality of storage means, each of which is provided so as to correspond to corresponding one of the image output section; first transfer means for sequentially transferring data collected in a predetermined block unit to the storage means; and second transfer means for sequentially transferring the data transferred to each storage means by the first transfer means to the corresponding image output means.
However, there has been the following problem in the above described prior art.
Since one microprocessor controls the generation of the image data with respect to all colors including cyan, magenta, yellow and black in the above described conventional color printers, performance of one microprocessor determines an upper limit of throughput of the printer, and hence it is difficult to realize a high speed color laser printer. Moreover, also in the prior art disclosed in the gazette, a central processing unit for controlling the printing processing collectively is one, so that the prior art has a problem in terms of high speed processing similarly to the conventional color printer.
The object of the present invention is to provide a printing apparatus which enables a high speed color printing by controlling image generation by use of micro processors provided individually for colors of cyan, magenta, yellow and black. The object of the present invention is also to provide a color image printing method.
A printing apparatus of the present invention, which forms a color image on a printing medium, comprises a plurality of main control means provided for corresponding colors, each of which generates image data for corresponding one of the colors; a plurality of storage means provided for the corresponding main control means, each of which stores the image data for corresponding one of the colors; a plurality of storage control means provided for the corresponding storage means, each of which controls writing/reading of the image data for corresponding one of the storage means; a plurality of video output control means provided for the corresponding storage control means, each of which outputs the image data as a video signal, the image data being supplied from the corresponding storage control means; and a plurality of image generating means provided for the corresponding video output control means, each of which generates an image based on the video signal output from the corresponding video output control means.
The printing apparatus of the present invention generates image data for each of the colors by corresponding one of the plurality of main control means provided for the corresponding colors. Next, each of the image data for the corresponding colors is stored by the plurality of storage control means provided for the corresponding main control means. Subsequently, the image data stored in each storage means is output as the video signal by each of the video output control means provided for corresponding one of the storage control means. Thereafter, each of the image generating means provided for corresponding one of the video output control means generates an image based on the video signal.
Generally, in the printing by the color laser, since a very large quantity of data needs to be processed, CPU has to show a data processing capability quadruple to 32 times as that of monochromatic laser printing. However, it is difficult to obtain inexpensive CPU which satisfies such requirement concerning the data processing capability. Accordingly, in the present invention, by using four inexpensive CPUs on the market for the four colors, high speed generation of color image data is enabled, and hence a high speed color laser printer can be provided.